Otitis media: Immunology and vaccines

Otitis media is one of the most common pediatric health care problems worldwide and accounts for more office visits, surgical interventions and drug purchases than any other disease in early childhood. Recent reports have revealed the middle ear as an excellent example of the function of innate immunity in mice and humans. The middle ear mucosa alerts the host of the invading pathogen to build up the first defense responses immediately by sensing pathogen-associated molecule patterns via pattern recognition receptors such as the Toll-like receptors (TLRS). They produce immediate antimicrobial responses and cytokine release which results in inflammation, such as in acute or chronic otitis media with or without effusion. The healing process of the ear infection can be influenced by cross-talk between TLRs in different ways resulting in either augmentation or suppression of the immune response and thus the course of the disease. To prevent over-activation or non-response, TLR signaling network must be integrated, and it is controlled by negative and positive feedback loops, to form a proper immune response in the middle ear after infection. In this review, we focus on the involvement of the immune system and its impact for more effective vaccination strategies and immunotherapies in otitis media.